[lsan] Remove the LSan-specific verbosity flag.

It conflicted with the verbosity flag we had in common flags. We don't need an
LSan-specific flag anyway.

Also, shift some logging levels and remove some unnecessary code.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@197512 91177308-0d34-0410-b5e6-96231b3b80d8